Back to EveryPatent.com
| United States Patent |
5,137,484
|
|
Bohannon
|
August 11, 1992
|
Method of making a liquid crystal display construction
Abstract
A method of making a LCD panel system including selecting a pair of
substrate panels, forming a peripheral seal on one of the flat surfaces of
one of the panels to define an area on the panel surface, distributing
compressible optical spheres over the area, aligning one substrate panel
with the first and placing the second panel against the seal, in an
aligned condition with the other to form a chamber. The panels are pressed
together to form a fluid tight seal between the panels. Air is then
evacuated from the chamber and an optical fluid is introduced into the
chamber.
| Inventors:
|
Bohannon; William K. (San Diego, CA)
|
| Assignee:
|
Proxima Corporation (San Diego, CA)
|
| Appl. No.:
|
714439 |
| Filed:
|
June 13, 1991 |
| Current U.S. Class: |
445/25; 141/7; 141/82; 349/189 |
| Intern'l Class: |
G02F 001/133 |
| Field of Search: |
445/25
141/7,82
359/53,63,64,74,80
|
References Cited
U.S. Patent Documents
| 4091847 | May., 1978 | Sorkin | 141/7.
|
| 4922972 | May., 1990 | Watanabe | 141/7.
|
| 5029985 | Jul., 1991 | Suzuki et al. | 359/53.
|
| 5071231 | Dec., 1991 | Armitage et al. | 359/53.
|
Primary Examiner: Ramsey; Kenneth J.
Attorney, Agent or Firm: Kleinke; Bernard L., Potts; Jerry R., Waters; William P.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application relates to a copending patent application Ser. No.
714,440, filed Jun. 13, 1991, entitled "LIQUID CRYSTAL DISPLAY
CONSTRUCTION AND METHOD 0F USING SAME," which is hereby incorporated by
reference as if fully set forth herein.
Claims
What is claimed is:
1. A method of making a liquid crystal display panel construction,
comprising:
using a liquid crystal panel means having a layer of liquid crystal
materials;
providing a thin, flat sealable chamber means on said panel means extending
substantially parallel to said layer of liquid crystal materials;
evacuating said chamber to withdraw air therefrom;
flowing into said chamber means as it is being evacuated an optical fluid
having a refractive index substantially equal to refractive index of said
panel means, to cause the fluid to flow uniformly over said surface within
said chamber means without any substantial bubbles being formed in the
fluid; and
sealing said chamber means.
2. A method of claim 1, including heating said optical fluid before
introducing said fluid into said chamber.
3. A method of claim 1, wherein said heating is accomplished by using a
heat exchanger.
4. A method of claim 1, wherein said optical fluid is a fluid selected from
the group consisting of UV11-3, UV11-4M1, UV11-5, UV14, UV14-1, UV14-3,
UV15-7 and NYOGEL.
5. A method of claim 4, wherein said fluid has a thick, viscous gel
consistency.
6. A method of claim 1, wherein said fluid includes a dye.
7. A method of claim 1, including using optical spheres, said spheres
having a diameter slightly greater than the thickness of said chamber,
compressing said spheres within said chamber to fix them in place prior to
evacuating the chamber.
8. A method of claim 7, wherein prior to said compressing, distributing
said spheres over said area in a spaced apart manner.
9. A method of claim 7, wherein said compressing includes deforming said
spheres into generally ovoid shapes within said chamber means.
10. A method of claim 1, including fixing a polarizer to said panel means.
11. A method of claim 1, including providing means between said panels for
defining the thickness of said chamber means.
12. A method of claim 1, including providing chamber air evacuation means;
providing an opening in said chamber means;
connecting in fluid communication said evacuation means with said opening
into said chamber means;
subsequently removing said evacuation means; and
sealing said opening.
13. A method of claim 1, further including:
providing a means for introducing said fluid into said chamber;
providing an opening in said chamber means;
connecting in fluid communication said means with said opening into said
chamber;
pumping said fluid via said means into said chamber means to fill it with
said fluid;
removing said means from said chamber means opening after said chamber has
been filled; and
sealing said opening after said means has been removed.
14. A method of claim 1, wherein said fluid is an ordered optical fluid.
15. A method of claim 1, wherein said fluid is a non-ordered optical fluid.
Description
DESCRIPTION
1. Technical Field
The present invention relates generally to a method of making a liquid
crystal display panel construction having improved optical
characteristics.
2. Background Art
The above referenced related patent application discloses a liquid crystal
display panel construction, including a layer of ordered optical fluid,
for improving the optical characteristics of the panel construction. The
fluid is disposed in a fluid tight chamber within the panel construction.
A plurality of optically clear, compressible, optical spheres are disposed
within the chamber and thus are embedded within the fluid, to help serve
as spacers to maintain the chamber in a spaced apart relationship
uniformly.
The chamber is filled with the ordered fluid in order to aid in the
accomplishment of improved LCD panel system performance, and it is very
important that the air chamber be completely filled by the ordered fluid
and that no air bubbles are present. Such bubbles could provide unwanted
optical loss or aberrations. In addition, a suitable means of sealing the
chamber must be provided in order to maintain system integrity, proper
optical coupling, and to prevent leakage of the fluid from the system.
However, there is a problem in filling the chamber properly with the
optical fluid, in the form of a viscous gel, in order for the system to
achieve the desired improved optical coupling and reduced refraction,
reflection and light losses. In this regard, the thick, viscous gel must
be applied in a thin, uniform manner over the entire surface to be coated
without any bubbles, in a mass production mode of manufacturing.
The problem of filling completely the chamber is made even more perplexing
by virtue of the fact that the more suitable gels for some applications,
are very viscous, and thus do not flow readily.
Thus, it is difficult to get the gel to flow in a desired manner uniformly,
without the introduction of the unwanted bubbles. As a result, the
requirement for filling the chamber with the gel becomes difficult, if not
impossible, to achieve.
Therefore, it would be highly desirable to have a method of making an
improved LCD panel construction, which would provide a fluid tight
chamber, filled completely with an optical fluid, such as a viscous gel,
and free of any unwanted elements, such as air bubbles.
In addition to the above mentioned limitations in conventional LCD system
construction methods, the details of the internal chamber itself deserve
consideration. The inventive system utilizes conventional glass substrate
panels to form the top and bottom of the chamber. These panels are very
thin, having a thickness on the order of 0.5-1.2 mm. Thus, the panels may
well be unable to provide adequate support uniformly over the area of the
chamber, because of the fragility of the panels. Thus, the optical spheres
are important to serve as spacers. However, the tiny, light weight spheres
must be uniformly distributed over the area of the chamber, and
distributed through the optical fluid. Such added requirement makes the
construction even more difficult, if not impossible to accomplish.
DISCLOSURE OF INVENTION
It is an object of the present invention to provide a new and improved
method of making a liquid crystal display panel construction employing a
viscous optical fluid, wherein the fluid is admitted to the other
components of the construction in a uniform, desired manner.
It is a further object of the present invention to provide such a new and
improved method, wherein the optical fluid is admitted free of unwanted
elements such as air bubbles, with minuscule optical spheres embedded
uniformly through the fluid.
It is a still further object of the present invention to provide such a
method for enclosing the optical fluid within a chamber of the display
panel construction in a fluid tight manner.
Briefly, the above and further objects are realized by providing a method
of making a liquid crystal display panel construction by applying a vacuum
to a chamber of the construction, and to admit a viscous optical fluid to
the chamber for causing the fluid to flow therein in a uniform manner. If
desired, optical spheres can be initially distributed throughout the
chamber, and clamped in place therewithin to fix them in position as the
fluid flows into the chamber.
The present invention affords several advantages. For example, the chamber
can be evacuated at the same time the optical fluid is being introduced
into it, thereby insuring an even distribution of fluid throughout the
chamber, and the elimination of air bubbles from the chamber.
In addition, the use of compressible optical spheres, when required,
provides structural support at a great number of points, for the
components forming the thin chamber.
BRIEF DESCRIPTION OF DRAWINGS
The above mentioned and other objects and features of this invention and
the manner of attaining them will become apparent, and the invention
itself will be best understood by reference to the following description
of the embodiment of the invention in conjunction with the accompanying
drawings, wherein:
FIG. 1 is a diagrammatic view of a stacked liquid crystal display panel
construction, according to the present invention;
FIG. 2 is a diagrammatic view of a liquid crystal display computer screen
construction, according to the present invention; and;
FIG. 3 is a diagrammatic view of a double super twisted liquid nematic
display panel computer screen, constructed according to the present
invention;
FIG. 4 is a diagrammatic view illustrating the panel construction of FIG. 1
in the process of being constructed according to the method of the present
invention; and
FIG. 5 is a diagrammatic view illustrating the panel construction of FIG. 1
in a further state of completion according to the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring to the drawings, and more particularly to FIG. 1 thereof, there
is shown a stacked liquid crystal display panel construction 10 of the
present invention. The construction 10 includes a pair of liquid crystal
display panels A and B. Liquid display panel A includes a polarizer 11, a
protective glass substrate plate 13, a layer of liquid crystal material 18
in the form of a matrix of liquid crystal pixel elements, and another
protective glass substrate plate 19.
The liquid crystal display panel B includes a protective glass substrate
plate 15, a layer of liquid crystal display material 26 in the form of a
matrix of liquid crystal pixel elements, another protective glass
substrate plate 27 and a polarizer 28. The polarizers, such as the
polarizers 11 and 28 are generally mylar sheets which are laminated on the
exterior surfaces of the glass substrate panels 11 and 28.
The LCD panels are each assembled and function in a conventional manner.
Also, the polarizers are conventional, and function with the LCD panels in
a known manner. The panels and polarizers are generally rectangular in
shape, and are thin and flat in their configuration, as is well known in
the art.
The liquid crystal display panels A and B are fixedly joined together by a
peripheral seal 17, which is composed of a suitable elastomeric material.
The seal 17 extends between the glass plates 13 and 15, which are
substantially larger than the other parts of their respective panels. A
spacer 21, extending peripherally adjacent to the seal 17 composed of
suitable opaque material, is interposed between the glass substrate plate
19 of panel A and the glass substrate plate 15 of panel B to maintain the
panels in a spaced apart relationship. A polarizer 23 is attached to the
inner surface of the glass substrate plate 19 and is surrounded
peripherally by the spacer 21. The polarizer 23 and the glass substrate
plate 15, together with the spacer 21, define a thin, generally
rectangular chamber 24.
In addition to the seal 17, a peripheral seal 12 is disposed between the
plate 19 and the plate 13 to join the seals and to confine the liquid
crystal material 18. Another peripheral seal 22 is disposed between the
plate 15 and the plate 27 to join the plate and to confine the liquid
crystal material 26. The seals 12 and 22 are similar in composition to the
seal 17.
If it is desired to maintain accurate spacing within the chamber, optical
spheres, such as the spheres 31, 32, 33 and 34 are disposed randomly
within the chamber 24 to maintain uniform spacing between the plates 23
and 15. In accordance with the present invention, an optical fluid in the
form of a clear viscous gel material 37, having suitable optical
transmissivity characteristics, is disposed within the chamber 24 with the
spheres 31, 32, 33 and 34 being impeded therewithin. The gel 37
substantially fills the chamber 24 to form a layer which extends in a
parallel, spaced-apart manner relative to the two matrices of liquid
crystal elements of the panels A and B to serve as an optical joint to
eliminate, or to reduce greatly unwanted light reflections, refractions,
or other losses.
The optical spheres, such as the spheres 31, 32, 33 and 34, when disposed
within the chamber 24, hold the panels A and B in a predetermined, spaced
apart relationship. A plurality of spheres are utilized, and they are
distributed randomly in a monolayer, throughout the chamber 24.
The optical spheres are slightly deformable and compressible, each having a
diameter which is slightly greater than a desired height t of the chamber
24. In assembling the construction 10, a bead diameter slightly larger
than the height t of the chamber 24 is selected so that, when the panels A
and B are pressed together during assembly of the system 10 as more fully
described in the above referenced copending application, the spheres
assume a generally ovoid or flattened shape when they become deformed
between the panels A and B. Of course, after assembling the construction,
the glass substrates, such as the glass plates 23 and 15, fix the spheres
in position by virtue of compression of the spheres by the glass
substrates.
Thus, the optical spheres become fixed in a random monolayer distribution
within the chamber 24 where they support the system 10 components and aid
in maintaining the desired height t of the chamber 24.
In addition to their support and separating functions, the spheres are
capable of responding, with the liquid crystal material, to thickness
changes resulting from temperature variations.
In one form of the invention, the spheres, in their unstressed condition,
are essentially perfectly spherical particles composed of cross linked
polymers, principally divinyl benzene, having a specific gravity and
thermal expansion coefficient close to that of the optical gel material. A
suitable bead is marketed under the trademark MICROPEARL SP. This bead is
manufactured by Sekisui Fine Chemical Co. of Japan.
In addition to the spacing and supporting functions described above, the
spheres aid in correcting any unevenness of glass substrate surfaces,
while maintaining the microscopic uniformity of the liquid crystal layer.
The spheres are substantially invisible due to their transparency, and
have similar optical transmissivity characteristics to the glass
substrates.
In this regard, the optical gel 37 has an index of refraction, which is
substantially equal to the index of refraction of the inner surfaces of
the stacked and joined panels A and B, the spheres and the polarizers 11
and 28.
If the desired optical characteristics of the construction 10 so require,
the gel 37 can be an ordered fluid having anisotropic properties, such as
birefringence. In some applications, the gel may be treated to accept an
appropriate dichroic dye, thereby imparting dichroic polarizing
capabilities to the gel 37 and eliminating the need for a dichroic filter
in the construction 10. Thus, the gel has a broad capability for allowing
the designer of the construction 10 to change or augment the total
birefringence of the construction 10 by adding additional birefringence by
modifying the birefringent optical characteristics of the gel 37. Thus,
the augmented birefringent characteristics can be utilized to optimize, or
at least to improve greatly the function of the combined panels A and B,
by matching the optical characteristics of the gel 37 to the specific
desired wavelength of light being transmitted. Hence, the gel has
significant utility for stacked LCD display systems.
In addition, the birefringence of the gel 37 can be used to change the
elliptical nature of polarized light leaving an LCD panel due to the
birefringent nature thereof. This characteristic can be used to eliminate
unwanted color components, as well as increasing the overall contrast and
transmissivity of the LCD panels.
The surface preparation methods depend upon the optical characteristics of
the optical coupling gel. If a gel with isotropic optical properties,
either in the index of refraction or spectral absorption, is selected,
then the surface must be clean and flat to normal tolerances, within the
chamber 24. If the gel is chosen to contain anisotropic optical properties
such as birefringence or dichroic dyes, then the inner surfaces of the
chamber 24 must be prepared to insure that the optical gel molecules align
properly to enable the desired use of the optical anisotrophy. This
alignment feature can be achieved by either a light chemical etch, or
other reaction, or through the use of an additional printed-on polymer
alignment layer, similar to that used in conventional LCD manufacturing
techniques. Additionally, the outer surface of any necessary polarizers
can be used as an alignment layer with a light rubbing technique.
The seal 21 for the optical gel is formed by printing or silk screening on
a seal pattern to one or both of the inner surfaces of the chamber of the
LCD panels A and B.
In connection with the spacing of the chamber 24, depending upon the type
of optical anisotrophies in the optical coupling fluid, the spacing
between the LCD panels is somewhat critical. If an optical coupling gel
with a very small birefringence is selected, than any normal variations in
the coupling chamber does not affect the overall performance, since the
optical retardation is the product of the birefringence and the chamber
dimension t, with the variations being a small percentage of the chamber
dimension t. However, if an optical gel is chosen with a relatively large
birefringence, then the dimension t must be small and the variations must
be small to prevent nay uneven color variations caused by excessive
changes in the overall optical retardation. To maintain the chamber
variation in the case where large birefringence gels are employed, the
spherical spacers help maintain the desired critical dimension t.
A number of commercially available gels are suitable. For example, gels
designated as ZLT-3126, ZLT-2666 and ZLT-2804, manufactured by E. Merck
Darmstadt are satisfactory. Some of the characteristics of the three gels
are depicted in the following Table 1.
TABLE 1
______________________________________
MIXTURE: ZLI-3126 ZLI-2666 ZLI-2806
______________________________________
S-N (.degree.C.) -7 <-20 <-30
Clearing point (.degree.C.)
+63 +70 +100
Viscosity (mm.sup.2 s.sup.-1) 20.degree. C.
20 45 87
Viscosity (mm.sup.2 s.sup.-1) 0.degree. C.
62 153 200
Viscosity (mm.sup.2 s.sup.-1) -20.degree. C.
-- 830 1170
Viscosity (mm.sup.2 s.sup.-1) -30.degree. C.
-- -- 3700
Viscosity (mm.sup.2 s.sup.-1) -40.degree. C.
-- -- cryst.
K.sub.3 /K.sub.1 +20.degree. C.
1.21 -- --
K.sub.3 /K.sub.2 +20.degree. C.
2.3 -- --
V.sub.(10.0.20) 2.74 DAP 1.7 DAP 1.9
V.sub.(80.0.20) 3.24 -- --
V.sub.(90.0.20) 4.04 -- --
Temp. dep. (mv/.degree.C.) (0-40.degree. C.)
22.4 -- --
Temp. dep. (%/.degree.C.) (0-40.degree. C.)
0.81 -- --
(V.sub.60 /V.sub.10 -1) 100 (%)
18.8 -- --
(V.sub.90 /V.sub.10 -1) 100 (%)
47.7 -- --
M20 1.77 -- --
M0-40 2.38 -- --
M0-40 1.77 -- --
______________________________________
In addition to the gels discussed above, other gels, such as UV11-3,
UV11-4M1, UV11-5, UV14, UV14-1, UV14-3 and UV15-7 manufactured by Master
Bond, Inc. of Hackensak, New Jersey, are suitable. These gels are viscous
and optically clear. In addition, they are good adhesives. Thus, the gels
aid in bonding the panels A and B together. Typical properties of the
UV15-7 gel are listed in Table 2.
TABLE 2
______________________________________
Color, uncured colorless transparent
compound, 25.degree. C.
Viscosity, uncured 6,000-10,000
compound, cps, 25.degree. C.
Specific gravity, 25.degree. C.
1.20
Non-volatile content, %
100
Hardness, Shore D, 25.degree. C.
>50
Tensile strength, psi, 25.degree. C.
2830
Elongation, %, 25.degree. C.
10-15%
Thermal expansion coefficient/.degree.C.
18-10.sup.-5
Specific resistance, ohm-cm, 25.degree. C.
1 .times. 10.sup.16
Refractive Index 1.47
______________________________________
The foregoing mentioned optical fluids are ordered fluids. A non-ordered
optical fluid may also be employed. In this regard, NYOGEL OC-431A
marketed by William F. Nye, Inc., of New Bedford, Mass., is a suitable
non-ordered optical fluid.
NYOGEL OC-431A optical fluid is a crystal clear, gel-like, optical coupling
compound. The presence of air at the junction of the two LCD panels A and
B tends to cause significant light refraction due to the large
differential optical impedance that exists between air and the panels.
Optical coupling fluid OC-431A is formulated with the requisite optical
properties of clarity, purity, and refractive index to minimize optical
losses.
The following is a Table 3, illustrating the properties of NYOGEL OC-431A,
as follows:
TABLE 3
______________________________________
Color Crystal Clear
Appearance Smooth, Transparent
Refractive Index at 25.degree. C.,
1.463
Sodium D line, 5893A
dN.sub.D /dt (-40 to 80.degree. C.)
-0.0003/.degree.C.
Dispersion N.sub.F -N.sub.c
<0.012
(Hydrogen F Line = 486.1
nanometers; Hydrogen C Line =
656.3 nanometers)
Consistency. 235 to 265 (Converted to
Unworked Penetration per
full scale penetration)
ASTM D-1403, 1/4 Scale
Oil Separation, 24 hrs at
None
100.degree. C.
Evaporation, 24 hrs at
2.8%
100.degree. C.
Dropping Point (Melting
None
Point)
Specific Gravity at 25.degree. C.
1.06
Pour Point of Base Oil
-62.degree. C.
Viscosity of Base Oil at -
23,684 cs
29.degree. C.
Thermal Coefficient of
0.0006 cc/cc/.degree.C.
Expansion
______________________________________
Apparent Viscosity as a function of Temperature:
Conditions: Brookfield Viscometer Model HBT-2X, 1 RPM,
T-A Spindle.
Degrees Centigrade
Poises
______________________________________
-40 44,373
-20 23,360
0 20,576
25 14,880
40 10,656
80 8,160
______________________________________
In constructing the LCD panel system of the present invention, standard LCD
components are selected, and prepared in order to have a leak tight seal
between the LCD components in a stack. The fluid tight volume formed when
two LCD panels are joined is then filled with an optical gel having the
desired optical properties. Two or more LCD panels can be joined in this
fashion, with thin optical gel volumes uniformly disposed between the
panels.
In selecting the optical gel for use in the system 10, it is important to
select a gel having a index of refraction that reasonably matches the
index of refraction of the inner surfaces of the LCD panels, including any
polarizers. When such matching is accomplished, optical coupling is
achieved, thereby allowing the optimum light transmissivity through the
stacked LCD panel system.
In addition to the optical gel qualities discussed above, the optical gel
can have other optical properties for a particular design of a stacked LCD
system. These additional properties may be optical and anisotropic and
spectral filtering, with either isotropic dyes or dichroic dyes. The
addition of optical and isotropic dyes to the optical coupling gel allows
the system designer to change or augment the total birefringence of the
LCD system with additional birefringence from the optical coupling gel and
path length (coupling thickness). This augmented birefringence can be used
to optimize performance for the specific wavelength of light selected for
transmission through the system. For example, stacked systems have been
constructed to switch in successive stages through the following colors:
red, green and blue.
In addition to the foregoing, the birefringence of the optical gel can be
utilized to change the generally elliptical nature of polarized light
leaving the LCD panel. This characteristic can be used to eliminate any
unwanted color due to birefringence of the LCD panel, as well as
increasing the panel's overall contrast and transmissivity.
Considering now the method of making the construction of the system 10,
with reference to FIGS. 4 and 5, an initial determination must first be
made of the system optical requirements. Following this, system
components, such as glass substrate plates and polarizers, are selected.
In some instances, depending on system requirements, such as the optical
characteristics of the system and the optical gel selected, preparatory
steps must be made. Such steps include preparation of the glass plates,
prior to the construction of the construction 10. For example, if a gel
with isotropic optical properties, either in the index of refraction or
spectral absorption, is selected, the substrate glass surface must be
clean and flat to normal tolerances. If, on the other hand, the optical
gel is selected to contain anisotropic optical properties, such as
birefringence or dichroic dyes, the contacting surfaces of the glass
plates must be carefully prepared to enable the optical gel molecules to
align properly, thereby achieving the desired use of the anisotropic
optical properties.
This alignment characteristic can be achieved by chemically etching the
glass plates or by using an additional conventional printed on polymer
alignment layer (not shown). In addition, the inner surface of the glass
plates and, the outer surface of any polarizers, can be used as alignment
layers after their surfaces have been treated by a conventional rubbing
process.
With reference now to FIG. 4, there is depicted the construction 10 of FIG.
1 in the process of being assembled according to the method of the present
invention. In this regard, the optical spheres, such as the sphere 36, are
being introduced to the chamber 24.
In order to accomplish the filling of the chamber 24 with both the spheres
and the optical gel, the construction 10 is assembled in two parts, which
are later joined at the chamber. In this regard, the lower portion only of
the construction 10 is illustrated in FIG. 4. The lower portion includes
the panel B, with the spacer 21 disposed on the outer surface of the glass
plate 15.
The seal 17 is composed of a suitable material to form a fluid tight bond
between the glass plates. The seal 17 may be a suitable elastomeric
material, or a suitable epoxy.
The spacer 21 has a thickness equal to the desired thickness t of the
chamber 24.
The spacer 21 is fixed to the surface of the glass plate 15 by any suitable
technique, such as applying an adhesive, to define thereby the side walls
and bottom of the resulting chamber 24 (FIGS. 1 and 5).
The next step in the construction of the construction 10 is to attach an
evacuation system 51 to an opening 57 at one corner of the rectangular
spacer 21, and a fluid introducing system 44 through an opening 43 at an
opposite corner of the spacer 21. The evacuation system 51 includes a
conduit 53 connected in fluid communication between the area of the glass
15 defined by the spacer 21, and the inlet of a pump 54. The fluid
introducing system 44 includes a conduit 45 connected in fluid
communication with the interior space defined by the spacer 21, and a
heater 48. The heater 48 is in the form of a heat exchanger for preheating
the optical fluid entering the interior of the spacer 21. A pump 46 has
its outlet connected to the inlet of the heater 48, and has its inlet
connected to a source of optical fluid (not shown).
The optical spheres such as the optical sphere 36, are introduced to the
outer surface of the glass plate 15 within the spacer 21. The spheres are
distributed randomly and generally uniformly over the surface of the
substrate plate 15, within the boundaries defined by the spacer 21. The
spheres are delivered from a sphere source, not shown, where the spheres
are fed under pressure, through a delivery tube 42 for application to the
substrate surface. The spheres are distributed in a monolayer and are
applied at a suitable rate. It will be noted, with reference to FIG. 4,
that the spheres are of a spherical configuration at the time of
application to the substrate panel 15, and have a diameter slightly
greater than the thickness of the resulting chamber.
With the spheres in place, and after insuring that the spheres are in a
desired mono layer configuration in a generally uniformly distributed
spaced apart manner, the polarizer 23 and the glass plate 19 are aligned
with the substrate plate 15 and pressed into position so that the
polarizer 23 completely fills the area defined by the spacer 21. As shown
in FIG. 5, the seal 17 is formed to bond the panel A, the spacer 21 and
the glass plate 15 in a unitary one piece configuration. The seal 17
further seals the chamber 24 in a fluid tight manner. It will be noted
with reference to FIG. 5, that after the glass plates have been pressed
together, the chamber 24 is formed. Since the chamber has a thickness t
which is slightly less than the diameter of the spacer bead 36, the
spheres are squeezed or compressed under tension into an ovoid shape, and
are held securely within the chamber 24 to prevent their movement when the
optical fluid is introduced.
After allowing sufficient time for the elastomeric seal 17 to form a fluid
tight bond, the optical gel 37 is delivered to the chamber 24. As
indicated above, it is very important that the gel 37 fill the entire
chamber and that no air bubbles remain after completion of the filling
process. In order to accomplish these objectives, a gel is delivered from
a gel source (not shown) to the pump 46. Since the gel 37 is generally of
a highly viscous consistency, for certain optical fluids, such as those
described in Table 1, it is helpful to heat the gel, utilizing the heater
48 before delivering the gel through the conduit 45 into the chamber 24 to
reduce its viscosity.
It is desirable to introduce the gel 37 near a corner of the chamber 24. As
the gel is delivered by the gel introduction system 44, the chamber
evacuation system 51 is activated.
When the pump 54 is turned on, air is evacuated from the chamber 24 through
the conduit 53. In this regard, pump operation should be regulated so that
the pressure drop is no more than several inches of water, thereby
permitting evacuation of the air from the chamber 24 in a convenient
manner. The evacuation of the air from the chamber is accomplished without
any dislocation of any of the optical spheres because, as indicated above,
the optical spheres are now in the ovoid shape of the spacer bead 38 of
FIG. 5. Thus, the spheres are fixed in position for separating and
supporting the substrate panels.
The systems 46 and 51 are operated until the chamber 24 is completely
filled with the optical gel 37. At this point, the evacuation system 51
and the gel delivery system 44 are turned off and are disconnected from
the system. After disconnection, the openings 43 and 57 are plugged with
an appropriate suitable elastomeric plug.
With reference now to FIG. 2, there is shown a liquid crystal display
computer screen construction 20 which is made according to the present
invention. The construction 20 is comprised of an LCD panel having glass
substrate panels 215 and 227, with a liquid crystal display material 226
disposed therebetween. A polarizer 228 is affixed to the surface of the
substrate 227, opposite the liquid crystal material 226. A peripherally
disposed spacer 221 separates the substrate panel 215 from a protective
glass panel 211. A peripherally disposed elastomeric seal 217 fixes the
panel 211 to the panel 215 and provides a fluid tight seal. A polarizer
223, disposed in a manner similar to the polarizer 23 of FIG. 1 is
attached to the inner surface of the plate 211. The polarizer 223, spacer
221 and the surface of the glass substrate 215 define a chamber 224. The
chamber 224 contains spheres 231, 232, 233 and 234 imbedded in an optical
gel 237. The optical gel and the optical spheres are disposed in a manner
similar to, and perform a similar function as their respective
counterparts of FIG. 1.
In addition to the seal 217, a peripherally disposed seal 222, having a
composition similar to that of the seal 217, fixes the substrate 215 to
the substrate 227 and confines the liquid crystal material 226.
With reference now to FIG. 3 there is depicted a double super twisted
liquid nematic display panel computer screen construction 30 which is made
according to the present invention. The construction 30 is comprised of a
pair of LCD panels A and B. The panel B includes a polarizer 328, a glass
substrate panel 327 and a liquid crystal material layer 326 disposed
between the substrate 327 and another glass substrate panel 315. The LCD
panel A includes a glass substrate panel 319 having one surface in contact
with the glass substrate 315. A layer of liquid crystal material 318 is
disposed between the substrate 319 and yet another glass substrate 320. A
peripherally disposed spacer 321, similar in composition and function to
the spacer 21 of FIG. 1, is disposed between the glass substrate 320 and a
protective glass plate 313 to form a chamber 324. A polarizer 323 is
disposed in the chamber 324 inside the spacer 321. An optical gel material
337 and optical spheres 331, 332, 333 and 334 are disposed within the
chamber 324 in a manner similar to, and perform a similar function as
their respective counterparts of FIG. 1.
In addition to the seal 317, peripherally disposed 322 and 324, having a
composition similar to that of the seal 17 are disposed, respectively,
between the substrate 320 and the substrate 319, and the substrates 327
and 317. The seals 322 and 324 fix the respective substrates together and
confine, respectively, the liquid crystal material 318 and 326.
While particular embodiments of the present invention have been disclosed,
it is to be understood that various different modifications are possible
and are contemplated within the true spirit and scope of the appended
claims. There is no intention, therefore, of limitations to the exact
abstract or disclosure herein presented.
Top